Abstract: :
Purpose:Linezolid (LN) is a synthetic antibiotic of the oxazolidinoneclass with inhibitory activity against gram–positive bacteriaincluding methicillin–resistant Staphylococcus aureus(MRSA), vancomycin–resistant enterococci (VRE), and penicillin–resistantStreptococcus pneumoniae. Linezolid also exhibits activity againstsome anaerobes including Propionbacterium acnes, Peptostreptococcusspp. Bacteroides fragilis, C. difficile, and C. perfringens.We evaluated the intravitreal toxicity of 400 mcg/0.2 ml concentrationof linezolid in albino rabbitsMethods: One eye of 17 New Zealand white rabbits was injectedwith either 400 mcg of LN (13 eyes) or balanced salt solution(4 eyes). An anterior paracentesis was performed prior to theinjection to prevent an intraocular pressure (IOP) rise. Post–injection,fundus exams were performed and intraocular pressures takenon days 3, 14, and 56. The rabbits were sacrificed and the globesenucleated after 3 days (4 eyes), 14 days (3 LN; 1control),and 56 days (6 LN; 3 control). Histopathologic examination ofthe eyes was performed and the retinal and ocular changes evaluatedusing a semiquantitative score in a masked fashion.Results: On fundus exam, no eye exhibited signs of intraocularinflammation or precipitation. The IOP’s were all withinthe normal range (15–22 mmHg). Histopathologic examinationshowed trace to 1+ vacuolization in the nerve fiber layer (6LN eyes; 3 control eyes) or trace to 1+ (1 eye 2+) ganglioncell loss. (3 LN eyes, 0 control eyes). The remaining retinallayers and ocular structures were unremarkable.Conclusions: 400 mcg per 0.2ml intravitreal linezolid appearsto be safe and well tolerated in rabbit eyes. Further studiesshould be performed to investigate whether intravitreal linezolidmay be a viable alternative to intravitreal vancomycin in theprevention and treatment of endophthalmitis